The plan is to develop a new technique for epidural blockade using an objective measure. The current "loss of resistance" technique depends on subjective feel of the anesthesiologist. Misinterpretation of this feel can result in complications such as dural puncture and misplacement of the needle tip. The spinal cord ends at L1 or L2. During puncture above this level may cause irreversible damage to the spinal cord. The electrical resistance of the epidural space in higher than the overlying ligaments. The electrical resistance of the epidural space in higher than the overlying ligaments. The epidural space can be identified by a sudden increase in tissue impedance. To measure the tissue impedance, a constant current will be passed between an epidural needle and a reference electrode. The configuration of the electrode will be used to identify the epidural space. The impedance technique will be considered effective if the time to start surgery can be shortened. Misplacement can be recognized immediately and the needle reinserted. It will not be necessary to wait to see whether the block works and repeat the procedure if not. We expect to see a reduction in the rate of complications, (dural puncture, failed blocks, etc).